Quality of life and air quality are important for citizens all around the world, but how do you know what your environment is really like?

Be sure to check out the followup to this write-up on collecting real-time air quality sensor data from the rooftops of city government vehicles in Washington, D.C.

See this article for more on how public transit can be used to gather real-time air quality information in urban areas!

The air we breathe every day has volatile organic compounds (VOCs) such as methane (from human breath), alcohol (cleaning supplies), formaldehyde (materials for building), ketones (paints), esters (glues), and terpenes (perfume). These are harmful to human health so:

  • How can we find out how much bad air we’re breathing?
  • Are there areas that are better for us to be when we’re outside?
  • If you had the choice of where to go for an outdoor activity, would you choose based on air quality?

I was curious about this so I conducted a study in the Los Angeles, California, area using the Valarm app and the Yocto-VOC sensor. Valarm compatible sensors are available at shop.valarm.net. You can follow these steps and do the same thing in your neighborhood or area of interest to know your outdoor and indoor air quality (IAQ).

For some people the Los Angeles area is notorious for pollution, but LA covers a lot of area so which parts of town are more dangerous for your health? Air quality can be observed to vary dramatically from the west end of the city (where the ocean is) to the east end, where mountains seem to trap pollutants.  There’s also variability from the north to south in air quality (and other health factors). My curiosity about this led to a presentation at the Vespucci Institutes: Synthesizing Population, Health, and Place on Catalina island. The pink dots in the map below show the areas where I collected Valarm VOC data.


Los Angeles, California, a diverse and sprawling city with dramatic air quality differences between each region. [Esri ArcGIS]

Some residential neighborhoods like El Segundo, California, are surrounded by chemical emitters such as refineries, airports, busy roads and freeways, and sewage treatment plants. Below are a couple pictures of the city of El Segundo taken on a Valarm data collection trip.

ElSegundo2-1 ElSegundo3-1



To do personal environmental monitoring with Valarm I plugged the Yocto-VOC into an Android device with the Valarm Pro app then placed the sensor in my jacket before I ran and walked around the different neighborhoods.




I used Valarm’s interval timer to collect data about the environment every 15 seconds. Next the Valarm data was uploaded to the Valarm Tools website where I could see the mobile data acquisition points and view graphs of sensor data.


Volatile organic compounds (VOCs) in Santa Monica, California, using Valarm Tools.



Graph of Valarm VOC data on the Valarm Tools website.


Then I downloaded the VOC and air quality data in KML format from Valarm Tools in order to see it in 3D with Google Earth. [Tutorial here: How To Import Valarm Data Into Google Earth]


Downloading Valarm data in KML format for 3D Visualization in Google Earth.


Now I can see the volatile organic compounds (VOCs) and their various ppm levels on a 3D globe.


Volatile organic compounds (VOCs) near University of Southern California (USC) in downtown Los Angeles, California.


Volatile organic compounds (VOCs) in El Segundo, California. El Segundo is boxed in by a Chevron refinery, LAX airport, sewage treatment plants, and the busy 405 freeway!

Volatile organic compounds (VOCs) in Santa Monica, California.

Volatile organic compounds (VOCs) in Santa Monica, California.


Volatile organic compounds (VOCs) in Palm Springs, California.


And you can do spatial interpolation with GIS analysis methods like inverse distance weighting (IDW) and kriging to create pollution maps.


Esri ArcGIS with spatial interpolation (inverse distance weighting, IDW) of VOC data gathered by the Valarm app.


Valarm mobile sensor data acquisition for analysis with Esri ArcScene and CityEngine.


The study shows parts of the Los Angeles, California, area that are potentially more dangerous, your results may vary! As a result of all this I’ll do my running and outdoor exercise in the western part of Los Angeles. This opens up the possibility for crowdsourced air quality measures since anyone can download and share their Valarm data as much as they like! Where in the world are the most dangerous levels of air quality?

Use Valarm to gather CO2 levels, water levels, temperature, humidity, and other sensor data. Valarm also does asset and fleet tracking, intruder detection, home monitoring, and more (monitor gardens, aquaponics, hydroponics, even agriculture and vineyards!). How do you use Valarm?

See this article for more on how public transit can be used to gather real-time air quality information in urban areas!